Kc and CN for forest groups/types

Hi there,
I am using a seasonal water yield model for two forested regions in the United States: the Southeast and the Pacific Northwest. My focus is exclusively on forested lands, excluding other land uses like urban areas, agriculture, and pasture. Consequently, my land use/cover group maps for the seasonal water yield model only contain information for forest groups, with each region featuring about ten different forest groups, such as Oak, Douglas-fir, Pine, and others.
I explored the available literature in search of Kc (crop coefficient) and CN (curve number) values. However, the literature primarily offers data for major land use categories and not specific forest groups. I would greatly appreciate it if anyone has suggestions or knowledge about sources that provide Kc and CN for forest types/groups.
Thank you in advance for your assistance.

Hi @hkarimi -

I’m curious what you mean by “excluding other land uses like urban areas, agriculture, and pasture.” I wouldn’t recommend running the Seasonal Water Yield model on a landscape where only forest is represented, and other land uses are completely removed. If urban/agriculture/pasture is set to NoData, then the flow path will be interrupted in these places, which will produce very messy and incorrect results. And you will be missing both upstream and downstream effects of these land uses (particularly in terms of water use/evapotranspiration), which impacts the result values calculated for forest.

It might be ok to combine urban/agriculture/pasture to a single value, if there is very little of it in the watershed, and you feel like they have similar properties, but I would still parameterize it.

And yes, it is hard to find data that differentiates forest types. I don’t know of any particular sources, so would love to hear from anyone who does.

~ Stacie

Hi there @swolny
Thank you so much for your quick reply and for the important point you mentioned. Appreciated it.
I am only working on forested lands of Southeast and Pacific Northwest and my case study do not include any other land uses. So, this is why I am just dealing with forest cover and its groups. But since I did not have kc for forest types, I considered value of “1” for all ten groups. I introduced forest map layer instead of land use map in SWR model. I did not not set other land uses as NoData because as I said my watershed only have forest. Is still make the problem you mentioned for my results?